Nanosatellite Attitude Stabilization Based on Decentralized Anti-windup Fault Tolerant Control

In this paper, a decentralized anti-windup (AW) fault tolerant control (FTC) scheme is presented to deal with a precise attitude stabilization and address the problem of spacecraft model uncertainties, external disturbances, actuator faults and saturation. To accomplish the desired mission requirement of attitude stabilization and fine pointing, the design will feature a nominal controller based on the classical Proportional Derivative (PD) control law. Additionally, the design of the decentralized FTC scheme will involve the design of an individual AW compensator for each channel representing each principal axis of the spacecraft attitude. The nominal controller is expected to attain stability of the system in an ideal condition while the AW compensator is formulated using Linear Matrix Inequality (LMI) and appended to the linearized control system for each individual loop. The design is inspired by ESTCube-2 nanosatellite model for attitude stabilization with reaction wheels (RW) momentum as control input to the FTC scheme with controller gain scheduling. Simulations are reported with reaction wheels momentum limit set as $1.5\times 10^{3}Nms$ to show the effectiveness of the developed FTC scheme.